The present invention relates to articles and compositions for imparting softening and anti-static benefits to fabrics in a laundry process. More particularly, alkyl ammonium carbamates applied to fabrics under typical home-use conditions provide excellent softness and static control.
It has long been recognized that certain chemical compounds have the capability of imparting softness to textile fabrics. These compounds, which are known generally as "softening agents", "fabric softeners", or "softeners", have been used both by the textile industry and by home and industrial laundry processors to soften finished fabrics, thereby making them smooth, pliable and fluffy to handle. In addition to the quality of softness, the fabrics have a reduced tendency to static cling and are easier to iron.
Most commercial fabric softeners are optimally used in a detergent-free rinse bath. However, such use requires a separate laundering step, i.e., separate addition of the softener during the rinse cycle. Accordingly, there has been a continuing search for through-the-wash fabric softeners.
The softening agents which are usually employed in commercial fabric softener compositions are cationic surfactant compounds, commonly quaternary ammonium compounds having at least two long alkyl chains. The positive charge on the softening compound encourages its deposition onto the fabric substrate, the surface of which is usually negatively charged. Unfortunately, the cationic softeners form a scumlike, non-softening complex with common anionic detergents. With nonionic detergents, too much of the softener is removed during the washing and rinsing cycles and the little remaining on the fabrics has no substantial softening effect.
The present invention avoids the use of cationic softeners except as optional adjunct softeners. Rather, alkyl ammonium carbamate salts are employed as softeners. These carbamate salts do not readily dissociate in water and do not undesirably react with the common anionic detersive surfactants found in most commercial laundering compositions.
Softening agents are usually employed in liquid compositions, but powder, tablet and granular formulations are also known. In recent years it has become increasingly common to impregnate water-insoluble cloth or paper substrates with softening compositions. The substrate can then be added directly to an automatic dryer. During the course of the drying operation the active softening material is transferred to the fabrics being dried. The carbamate salts herein can be used in any of these forms to condition fabrics.
It is an object of the present invention to provide softening compositions and articles which are capable of imparting superior softness and anti-static properties to fabrics.
It is another object of this invention to provide softeners which can be added at the first step of the laundry process, i.e., in the laundry pre-soak bath or in the wash cycle, in the presence of an anionic surfactant.
It is another object of this invention to provide articles which can be added to a clothes dryer to impart improved softening and anti-static benefits to fabrics.
These and other objects are achieved by means of the alkyl ammonium carbamates disclosed herein.